Humans have become increasingly dependent on technology, particularly electronic devices. In the past decade, electronic devices have become more mobile, enabling people to use medical devices, cellular/satellite phones, laptop computers, and GPS as they move around cities or in the wilderness. At present, all of these devices run off of batteries which have limited lifetimes and add considerable weight to the device. The combination of limited lifetimes and large weight of batteries is particularly crucial to disaster relief workers, first responders, field scientists and explorers on prolonged expeditions. These individuals often must carry heavy packs (> 80 lbs), and much of the weight is replacement batteries. Millions of dollars have gone into developing a portable and renewable human-generated energy source but there has not been a solution. To solve this problem, we developed a passive device, the Suspended-load Backpack, which extracts mechanical energy during walking and then converts it to electricity. While carrying an 80 lb load, individuals can generate in excess of 7 W of electricity, and approximately 2 W with a 40 lb load. This is a significant because previously published attempts with devices fitted in shoes generated ~300-fold less (~20 W). The electricity generated by our backpack can be used to power equipment in real-time, and recharge batteries. Interestingly, metabolic experiments show that generating this electricity increases the metabolic rate by only 2-3%, and actually reduces the energetic cost for carrying a load. Further, carrying the load is ergonomically more comfortable with the Suspended-load Backpack than standard ones because of reduction in forces on the body, and thus should reduce common orthopedic injury. As backpacks represent a $295 million annual business, an electricity-generating backpack has substantial commercial value. Additional innovative design/engineering is necessary to bring the "proof of concept" to commercialization. [unreadable] SPECIFIC AIM 1: Reduce the weight of the Suspended-load electricity-generating backpack. [unreadable] SPECIFIC AIM 2: Make a mathematical/computational model of the electricity-generating backpack. [unreadable] SPECIFIC AIM 3: Develop circuitry to control damping, power portable devices and charge storage devices. [unreadable] There are equally compelling health/societal applications for the device in Developing Countries. A large percentage of the world's population lives off the electrical grid. Because of this, their drinking water is often contaminated with pathogens, they have no routine medical testing, nor access to vaccines. Many portable, low power devices have been developed which can provide a great improvement but what is missing is a small source of electricity. The backpack can provide sufficient power for: sterilizing water with portable UV lamps (SteriPen), help provide requisite refrigeration of vaccines, simple diagnostic tests, and communication devices in the case of emergencies. In Phase II a new, lighter and more efficient prototype will be developed and clinically tested, taking advantage of the improved technologies and understanding developed in Phase I. Electricity independence provided by our electricity-generating backpack is extremely important to disaster relief workers, forest fire fighters, field-scientists, explorers, environmental testers, and some first responders, all of whom who must function off the electric-grid. There are equally compelling health applications in Developing Countries. A large portion of the world population lives their whole lives off the electrical-grid: Hence their drinking water is often contaminated with pathogens, they have no routine medical testing, nor access to vaccines and medicines that must be refrigerated. Many portable, low power devices have been developed, and the backpack can provide the missing small source of electricity for: sterilizing water (UV; SteriPen), helping refrigerate vaccines, simple diagnostic tests, and communications in the case of emergencies. [unreadable] [unreadable]